The present invention relates to an electrophotographic copier in general, and more particularly to an electro-photographic copier of the type having a flexible strip-shaped latent-image carrier.
Electro-photographic copiers are known in the art which are of the type having an endless strip-shaped latent-image carrier that is trained about a plurality of rollers so that it travels in an endless path. The path has a portion in which the image carrier travels in planar condition past an image-forming station at which an image of an original to be copied is formed on the carrier. This type of copier requires that the latent-image carrier travel at a relatively high rate of speed and has to have rather complicated arrangements which prevent the carrier from slipping off the axial ends of the rollers about which it travels. These arrangements must necessarily be complicated because it is not merely sufficient to prevent such slipping-off, but it is also necessary to prevent the occurrence of damage to the readily damaged edge portions of the carrier.
Another copier of the type in question has a rotatable drum the periphery of which carries flexible photoconductive plates which engage the drum surface and are erected to a planar condition in the region of the image-forming station. These plates, as indeed the strip-shaped latent-image carrier of the first-mentioned copier, must be relatively frequently replaced because the relatively small quantities of photoconductive material on the carrier and the plates, respectively, means that the conductive material becomes spent rather quickly.
Another type of prior-art copier uses a strip-shaped latent-image carrier, i.e. a photoconductive carrier, which is pulled over a rotary body which is generally cylindrical and has a flat part. In this type of device it is necessary that--independently of the degree of wear of the photoconductive material on a particular increment of the carrier--the exposed increment of carrier must after each exposure be advanced from the flat part of the cylindrical body to the cylindrical part thereof, so that for each exposure a new carrier increment must be employed. This of course results in a very high rate of use of photoconductive material.
The prior art devices are, therefore, definitely in need of further improvements as the above brief description shows.